1. Field of the Invention
The present invention relates to a tape cartridge, and more particularly to a tape cartridge having a magnetic shielding member and a spring plate member for supporting a tape contacting pad both provided in the interior of the tape cartridge.
2. Description of the Prior Art
In conventional magnetic recording tape cartridges 1 having a head insertion opening 6, as shown in FIG. 1, a tape pressing pad assembly having a pressing pad 15 attached to a pad support plate 11 made of an elongated and resilient plate is mounted in the front part of the cartridge 1 so as to face the tape insertion opening 6 defined in the front wall of the cartridge for resiliently pressing a recording tape 4 to a magnetic head of a tape player. The tape pressing pad assembly is detachably mounted near the front wall of the tape cartridge in combination with a magnetic shielding plate 10 made of an elongated magnetic plate by merely putting the respective end portions of the plates on suitable base members provided on the bottom half 1a of the tape cartridge so that both plates 10 and 11 are parallel opposed each other.
In this arrangement, it is essential to mount the magnetic shielding plate 10 in position without any play in a vertical direction, a longitudinal direction or front and back directions of the cartridge and lateral direction or left and right directions. The displacement of the magnetic shielding plate 10 in the vertical direction or vertical play can be easily prevented when the top half and the bottom half of the cartridge are assembled together since the top and bottom of the magnetic shielding plate are regulated by the halves. The lateral play of the magnetic shielding plate can be limited by engaging both bent ends 13 of the magnetic shielding plate 10 with a pair of side ribs 25. However, it is a serious problem to prevent the play of the magnetic shielding plate 10 in the longitudinal direction keeping the workability of assembling the magnetic shielding plate in position. Since the pad supporting plate 11 is constrained by the magnetic shielding plate 10, if the magnetic shielding plate is undesirably displaced in the longitudinal direction or if the geometric position of the magnetic shielding plate is not accurate, the position of the tape pressing pad 15 with respect to the tape 4 changes, whereby the pressure of the recording tape 4 against the magnetic head applied by the tape pressing pad changes, resulting in a bad contact of the magnetic head to the recording tape and/or an abnormal tape advance.
Besides the problem mentioned above, there has been proposed to emboss one or more projections 14 in the rear face of the magnetic shielding plate 10 in order to reinforce the plate 10. Only one projection may be formed in the central part of the plate or a plurality of projections may be formed. As shown in FIG. 1. the magnetic shielding plate 10 is assembled in position by inserting the plate 10 in a space defined by the side ribs 25 and a reinforcing rib 21 of the bottom half 1a with the central projection 14 detachably contacted to a projection 29a of a boss 29. Thus, the magnetic shielding plate 10 can be constrained in the longitudinal direction by the three point engagement manner. The arrangement mentioned above facilitates mounting the magnetic shielding plate in position.
However, since the projections 14 must be formed by embossing, there may occur errors in the size of the projection 14 and/or the flatness of the surface of the projection 14, thereby resulting in an error of position of the end of the bent portion 13 of the magnetic shielding plate 10. As a result, there tends to occur difference of the pressure applied to the recording tape by the tape pressing pad assembly.